Generic fittings have at least one locking bar and one rotatable eccentric. The eccentric holds the at least one locking bar, in a manner in which it is spring-loaded, in engagement with a toothing of a toothed ring. The eccentric contour is designed to be self-locking, i.e. a transmission of force from the toothed segment to the eccentric under static load conditions or impulse loads does not lead to a rotation of the eccentric and as a result does not lead to an opening of the fitting. Unfavorable load conditions, however, in particular cyclical or vibratory stresses, may lead under adverse conditions to an undesired rotation of the eccentric and as a result to an undesired opening of the fitting.
When mounting a generic fitting, an eccentric angle which defines the angular position of the eccentric relative to a component of the fitting which is fixed in terms of rotation is used to monitor a fully locked position. Known eccentrics have the drawback that it is difficult to detect whether the measured eccentric angle is still within an admissible eccentric angular range defined by permitted component tolerances. Inaccuracies in terms of measurements and/or readings of the eccentric angle may lead to a false assessment of the fitting.
A generic fitting is disclosed in DE 10 2010 053 525 B3 in which, in a first contact point between a first eccentric cam and a first locking cam, a first wedge angle is defined, said first wedge angle being positive, and in a second contact point which is produced only under load between the second eccentric cam and the second locking cam, a second wedge angle is defined, said second wedge angle being negative. The positive wedge angle on the first cam pair serves for locking the locking bar and for compensating for tolerances. A normal force with an opening component transmitted from the locking bar via the first cam pair to the eccentric is compensated by frictional forces in a self-locking manner. The negative wedge angle on the second cam pair serves for blocking the rotation of the eccentric under load, as the normal force in this case has a closing component. In practice, it has been shown that this system consisting of a first and second wedge angle is very sensitive to tolerances.
A fitting with a locking bar is disclosed in DE 44 19 411 A1, said locking bar in each case having a bearing surface in two partial regions of the locking bar offset axially and radially to one another. An eccentric is provided for locking the locking bar and thus the fitting, said eccentric being floatingly coupled to a drive bushing. The eccentric comprises a cam with a clamping surface which continuously rises from one end to the other end of the cam and cooperates in a locking manner with one of the two bearing surfaces. The drive bushing comprises a further cam with a concentric interception surface which cooperates with the other of the two bearing surfaces. The two cams in the peripheral direction are only slightly offset relative to one another and during the locking of the fitting are rotated at the same time below the assigned bearing surfaces. As a result, with a small angle of rotation of the eccentric, the cam already bears with the clamping surface against the locking bar. This small angle of rotation makes it complicated to assess the locked state of the fitting in a reliable manner by using the eccentric angle.
EP 1 591 303 A2 discloses a further fitting with an eccentric which has two eccentric cams for supporting a locking bar. It is not disclosed how the eccentric cams have to be designed so that the locked state of the fitting may be assessed reliably using the eccentric angle.